1. Field of the Invention
The present invention refers to a process for the concurrent preparation of unsaturated or saturated .alpha.,.omega.-dialdehydes and .alpha.,.omega.-diacids. The present invention further refers to said dialdehydes and said diacids prepared by the aforesaid process.
2. Prior Art
In Italian Application No. 30939 A/76 corresponding to U.S. Pat. No. 4,177,214 the preparation is described of unsaturated .alpha.,.omega.-dialdehydes starting from the monoozonides of the corresponding polyunsaturated cycloolefins, while in Italian Applications No. 28802 A/75 corresponding to Italian Pat. No. 1,049,005 and No. 29682 A/78 corresponding to U.S. application Ser. No. 090,987, abandoned, the preparation is described of the .alpha.,.omega.-dicarboxylic acids, by oxidation of the corresponding dialdehydes or the corresponding aldehydo-acids.
In the preparation of the unsaturated .alpha.,.omega.-dialdehydes according to Italian Application No. 30939 A/76, the dialdehyde is obtained by selective reduction of the corresponding unsaturated ozonides, by means of hydrogen under pressure and of a particular catalytic system constituted by the combination of two metals, while in Italian Applications No. 28802 A/75 and No. 29682 A/78 the dicarboxylic acids are obtained by catalytic oxidation of the dialdehydes or the aldehydo-acids using air and a catalyst based on cobalt and/or silver.
The unsaturated diamines are obtained from the unsaturated dialdehydes by reductive amination; the saturated and/or unsaturated diamines and the saturated and/or unsaturated diacids may be used to prepare unsaturated polyamides, e.g. according to the Italian Application No. 26291 A/79 corresponding to German DOS No. 3037488 Al by the same Applicant.
It is obvious that in order industrially to produce said two monomers two production lines are required, the first one for preparing the diamines and the second one for preparing the diacids, which involves a double investment and an increased production cost.